Part of Made in India,Design Innovation

Workshop,2015

A  Fresh  New  Experience  in  

Project-­‐Making  and  Learning

PHYSICS INVESTIGATORY PROJECT ON

OR GATE USING TRANSISTORS

What  happens  when  in  an  industrial  plant,  one  or  more  parameters  exceed  the  safe  value?  In  this  case,  the  OR  gate  comes  to  the  aid  and  can  be  used  to  detect  any  parameter  value  (that  of  pressure  or  temperature)  going  above  the  threshold.  Consequently,  the  output  of  the  OR  gate  sends  a  command  signal  for  the  system  to  take  required  acMon.  A  2-­‐input  OR  gate  has  two  inputs  (A  and  B)  and  only  one  output  (Q).  

In  this  project,  you  will  make  an  OR  gate  logic  circuit  using  two  transistors  (Q1  and  Q2),  four  resistors,  an  LED  and  a  few  connecMng  wires.  The  emiTer  of  Q1  is  connected  to  the  emiTer  of  Q2.  Similarly,  the  collectors  of  the  two  transistors  are  connected  to  each  other.    Two  wires  are  connected  to  the  leV  leg  of  the  base  resistors.  Each  connecMng  wire  represents  the  input.  This  input  could  be  either  1  or  0,  where  1  

stands  for  Vcc  (posiMve/high  voltage)  and  0  stands  for  ground  (negaMve/low  voltage).

To  provide  the  respecMve  inputs,  the  truth  table  of  OR  gate  is  followed.

Input  A   Input  B Output  Q0 0 00 1 11 0 11 1 1

On  providing  the  inputs,  if  the  LED  glows  this  means  output  Q  =  1  or  high.  If  the  LED  does  not  glow,  the  output  Q  =  0  or  low.  AVer  verifying  the  experimental  outputs  in  four  different  cases  of  the  inputs,  we  do  the  ‘path  of  current’  analysis  and  reason  out  why  the  LED  glows  in  each  case.

Have  a  look  at  our  Project  Kit!

CoolJunk   is   India's   fastest   growing  DIY   (do-­‐it-­‐yourself)   kits   company   focused   on   project-­‐based   learning   in  science,   engineering   and   technology.  Having   20,000   users   in   India,  US,   Singapore,   Middle   East   and   New  Zealand,  the  CoolJunk  kits  are  known   for  quality,  innovaMon   and  high  producMon  value.  CoolJunk  has  been  featured   in   naMonal   and   internaMonal   journals   including   Wallstreet,   Yourstory,   Hindu   Business   Line,  NextBigWhat  and  was  tagged  as  the  coolest  Indian  start-­‐up  in  IAN  Bootcamp-­‐2011.  

You  may  also  refer  to  the  video:  OR  GATEFor  more  projects  visit  our  website:  CoolJunk  

Tools  and  Components  in  one  box.

Step  by  step  visual  instrucMons

Detailed  experiment  theory

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